Secrets of the pyramids: Researchers will use muon tomography to search for hidden chambers, construction methods

The Egyptian pyramids have fascinated historians, scientists, and researchers for thousands of years. Despite centuries of analysis and theory, however, our understanding of how the ancient Egyptians actually built the pyramids is woefully incomplete. Now, a team of Egyptologists has announced that it intends to use muon tomography to scan the interior of the Great Pyramid, with the hope of answering certain questions about how the structures were constructed. For centuries, it was thought that the Ancient Egyptian built the pyramids using a system of levers and massive amounts of slave labor. This is the account that Herodotus presented in his 5th century BC work, The Histories.

We now know that Herodotus’ account of slave labor was almost certainly wrong, while his description of the Ancient Egyptian method of raising the Pyramids was, at best, woefully incomplete. Herodotus may have lived 2500 years ago, but the Great Pyramid at Giza was built between 2580 and 2560 BC, roughly 2000 years before his time. Imagine asking a modern Italian contractor to provide a specific analysis of how the Romans built the Coliseum from 70-80 AD, and you’ve got an idea of the scope of the problem.

Part of what complicates our understanding of the Egyptian pyramids, however, is that the Egyptians didn’t build them all in the same fashion and they lost the technology and understanding they had used to build the pyramid complexes at Giza. Egypt’s knowledge of pyramid-building reached its apex in the Old Kingdom period. The few surviving pyramids of the New Kingdom are little more than a collection of mud and rubble held to shape by external facings. By the time Herodotus lived, pyramid building had been abandoned altogether.

The problem with the surviving pyramids is that there’s very little evidence of the support structures that must have existed to create them in the first place. The dominant hypothesis for years was that the Ancient Egyptians had relied on a series of external ramps (multiple types have been suggested). In the early 2000s, architect Jean-Pierre Houdin suggested that the pyramids might have been assembled using both internal and external ramps. In this model, the external ramps were used to lift the first 30% of the structure, which was assembled with internal ramps thereafter.

Evidence found during a 1986 microgravity survey of the pyramid may support this hypothesis. The French survey team that conducted the analysis found evidence of a spiral structure within the Great Pyramid that matches certain features Houdin predicted. While this is not considered definitive proof of any set construction technique, it illustrates how non-invasive scanning technology can gather information invisible to the human eye and shed light on how long-dead people constructed these monuments.

Muon tomography scanning has been used to peer inside nuclear reactors, but never as part of an archaeological expedition. The scanning project is expected to begin in November, 2016 and will use a combination of drone-mounted scanners, thermal imaging, and muon tomography to produce the most detailed 3D models of the pyramids of Khufu and Khafre (the largest and second-largest of the Giza Pyramids) ever built. The Bent and Red Pyramids will also be investigated. These pyramids are not as famous as the aforementioned Great Pyramids, but each represents an important step in Egyptian construction. The Bent Pyramid is called such because its angle of inclination changes sharply partway up the base, from an initial 54 degrees to a shallow 45 degrees.

Maybe the boss won’t notice

This change is thought to have been driven by the collapse of a steep-sided pyramid at Meidum, but investigating the internal structure of the pyramid could shed more light on whether the Egyptians corrected some of the evident building mistakes at Meidum as well. There are large timber beams inside the Bent Pyramid, which implies that workers were concerned about its stability and actively working to shore up the structure.

The Red Pyramid, named for the dusty red color of its interior limestone, is thought to be the first “true” pyramid the Egyptians constructed. A rare capstone of Tura limestone was found near the pyramid, though it’s not clear if the stone was ever actually intended for this pyramid (the angle of inclination is different than the Red Pyramid itself). Answering questions about these early pyramids will help researchers create more sophisticated timelines on the evolution of building technology throughout the Old Kingdom period.

If these investigations prove successful, we could be seeing the beginning of a sea change in archaeology across the world. We’ve previously covered how modern technology exposes ancient cities or leads to fresh evidence for old theories, but muon tomography and other sophisticated ground-scanning technologies could largely kill the need to dig at all — or at least allow researchers to create sophisticated models of the areas they want to reach. Imagine being able to plan a dig site in a way that minimized disruption of key surrounding artifacts or evidence because you could actually see the evidence before you ever picked up a shovel.